#region License
/*
 * HttpBase.cs
 *
 * The MIT License
 *
 * Copyright (c) 2012-2014 sta.blockhead
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#endregion

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.IO;
using System.Text;
using System.Threading;
using WebSocketSharp.Net;

namespace WebSocketSharp {
    internal abstract class HttpBase {
        #region Private Fields

        private readonly NameValueCollection _headers;
        private const int _headersMaxLength = 8192;
        private readonly Version _version;

        #endregion

        #region Internal Fields

        internal byte[] EntityBodyData;

        #endregion

        #region Protected Fields

        protected const string CrLf = "\r\n";

        #endregion

        #region Protected Constructors

        protected HttpBase(Version version, NameValueCollection headers) {
            _version = version;
            _headers = headers;
        }

        #endregion

        #region Public Properties

        public string EntityBody {
            get {
                if (EntityBodyData == null || EntityBodyData.LongLength == 0) {
                    return string.Empty;
                }

                Encoding enc = null;

                var contentType = _headers["Content-Type"];
                if (contentType != null && contentType.Length > 0) {
                    HttpUtility.TryGetEncoding(contentType, out enc);
                }

                return (enc ?? Encoding.UTF8).GetString(EntityBodyData);
            }
        }

        public NameValueCollection Headers {
            get {
                return _headers;
            }
        }

        public Version ProtocolVersion {
            get {
                return _version;
            }
        }

        #endregion

        #region Private Methods

        private static byte[] readEntityBody(Stream stream, string length) {
            if (!long.TryParse(length, out long len)) {
                throw new ArgumentException("Cannot be parsed.", "length");
            }


            if (len < 0) {
                throw new ArgumentOutOfRangeException("length", "Less than zero.");
            }

            return len > 1024
                   ? stream.ReadBytes(len, 1024)
                   : len > 0
                     ? stream.ReadBytes((int)len)
                     : null;
        }

        private static string[] readHeaders(Stream stream, int maxLength) {
            var buff = new List<byte>();
            var cnt = 0;
            void add(int i) {
                if (i == -1) {
                    throw new EndOfStreamException("The header cannot be read from the data source.");
                }

                buff.Add((byte)i);
                cnt++;
            }

            var read = false;
            while (cnt < maxLength) {
                if (stream.ReadByte().EqualsWith('\r', add) &&
                    stream.ReadByte().EqualsWith('\n', add) &&
                    stream.ReadByte().EqualsWith('\r', add) &&
                    stream.ReadByte().EqualsWith('\n', add)) {
                    read = true;
                    break;
                }
            }

            if (!read) {
                throw new WebSocketException("The length of header part is greater than the max length.");
            }

            return Encoding.UTF8.GetString(buff.ToArray())
                   .Replace(CrLf + " ", " ")
                   .Replace(CrLf + "\t", " ")
                   .Split(new[] { CrLf }, StringSplitOptions.RemoveEmptyEntries);
        }

        #endregion

        #region Protected Methods

        protected static T Read<T>(Stream stream, Func<string[], T> parser, int millisecondsTimeout)
          where T : HttpBase {
            var timeout = false;
            var timer = new Timer(
              state => {
                  timeout = true;
                  stream.Close();
              },
              null,
              millisecondsTimeout,
              Timeout.Infinite);

            T http = null;
            Exception exception = null;
            try {
                http = parser(readHeaders(stream, _headersMaxLength));
                var contentLen = http.Headers["Content-Length"];
                if (contentLen != null && contentLen.Length > 0) {
                    http.EntityBodyData = readEntityBody(stream, contentLen);
                }
            }
            catch (Exception ex) {
                exception = ex;
            }
            finally {
                timer.Change(-1, -1);
                timer.Dispose();
            }

            var msg = timeout
                      ? "A timeout has occurred while reading an HTTP request/response."
                      : exception != null
                        ? $"An exception has occurred while reading an HTTP request/response: {exception.Message}"
                        : null;

            if (msg != null) {
                throw new WebSocketException(msg, exception);
            }

            return http;
        }

        #endregion

        #region Public Methods

        public byte[] ToByteArray() {
            return Encoding.UTF8.GetBytes(ToString());
        }

        #endregion
    }
}
